KR100405224B1 - Method and material for the image-like placement of uniform spacers on flat panel displays - Google Patents

Abstract

Process and materials are described for selectively placing uniform spacers on a receptor. Spacer elements are placed on a receptor by selectively irradiating a thermal transfer donor sheet comprising a transferable spacer layer. The transferable spacer layer may include particles or fibers to form a composite. The particles may have a spacing dimension either greater than or less than the thickness of the transferable layer. When the spacing dimension of the particle is greater than the thickness of the transferable layer, then the spacing dimension of the particles control the spacing distance. The process and materials are useful in the manufacture of flat panel displays, particularly, liquid crystal display devices.

Description

Method and material for the imaging of uniform spacers in flat panel displays

Control of spatial spacing and mechanical forces within the structure of flat panel displays (ie liquid crystal displays, electroluminescent displays, vacuum fluorescent displays, field emission displays, and plasma displays) is often critical to the performance of the corresponding device. And coupling the physical spacers to the corresponding display. For example, in liquid crystal displays (LCDs), the polarization of light emitted from the display is controlled in part by the optical path length through the liquid crystal layer. In the current display technology, the thickness of the liquid crystal layer is determined by the spacers, which are particles (i.e., spherical beads or fibers), and columnar structures (i.e. posts or fillers). pillars), microribs, or the like. Spacers are becoming increasingly important with the need for lightweight and large format display. To obtain lighter display panels, transparent polymeric substrates that are much lighter than glass are commonly used. However, since the polymeric substrate is more flexible, spacers need to be denser to maintain a uniform thickness throughout the display panel. The most common and inexpensive way to control the thickness of a liquid crystal display is to irregularly deposit particles having a narrow size distribution throughout the surface of the substrate or alignment layer. This process has the obvious disadvantage of not being able to control the placement of the particles so that very many particles appear in the display window, thus reducing the amount of light that passes through the display. In many applications, the particles move without being fixed to the substrate, resulting in artifacts in the display cell area. Spray devices present additional problems in the manufacturing process. The displays are combined into Class 10 to 100 cleanrooms to meet the optical quality requirements for liquid crystal displays. By spraying particles on the surface, many particles move into the air, making it difficult to maintain grade 10-100 standards. The thinner the desired layer, the smaller the size of the required particles and the more difficult the operation or application.

One method for solving the problems in liquid crystal displays as described above is a method in which a photoresist material is adhered to a substrate, and imaged and developed to produce a spacer, as described in US Pat. JP2223922. This method allowed more accurate positioning of the spacers on the substrate, but the development step required additional steps in the process. In addition, liquid crystal development results in a spent developing solution to be treated. Many developers contain solvents or have a high pH index and must be handled or handled specifically to comply with federal and state environmental regulations. In addition, when a photoresist is used, it becomes more difficult to maintain a uniform thickness of the spacer. For example, a developer may etch more of the surface in one area than in another.

Another method for controlling spacing in liquid crystal displays is disclosed in US Pat. No. 5,268,782, where microstructured substrates are used both as substrates and spacers integrated into one device. In order to minimize interference in the window region, microstructured surfaces are typically composed of a series of parallel ridges (microridges). The ratio of spacers in the optical window is minimal, but the stripping effect is visible on the display. In addition, attaching liquid crystal of high viscosity becomes more difficult when microribs are used as spacers. For example, it becomes more difficult to add high viscosity liquid crystals without entrained air in which optical crystals are produced in the layer.

There is a need for methods and materials for accurate placement of spacers that are inexpensive, reliable, and function structurally without interference with the optical integrity of the display panel.

The present invention relates to methods and materials for placing spacers in receptors that provide uniform spacing and structural retention to flat panel displays. More specifically, the present invention relates to the precise placement of spacers using thermal transfer donor sheets and image radiation sources.

The present invention employs a method and a material for arranging spacers that function structurally in the receptor using thermal transfer donor sheets and image irradiation to accurately position uniform spacers at desired locations outside the display window. It solves the problem of the prior art.

The present invention provides a thermal transfer donor sheet comprising (a) a support, (b) a transferable spacer layer, and (c) an optical adhesive layer. At least one of the receptor, the support, the transferable spacer layer and the adhesive layer includes a radiation absorber that converts the image radiation portion into heat. Image irradiation provides a means for selectively transferring a transferable spacer layer to the receptor to form a spacer element in the receptor.

Other thermal transfer donor sheet constructions comprising (a) a support, (b) a lignt-to-heat conversion layer comprising a first radiation absorber, (c) a transferable spacer layer, and (d) an optional adhesive layer This may be provided. The thermal transfer donor sheet may optionally include a non-transferable intermediate layer interposed between the photothermal conversion layer and the transferable spacer layer. A second radiation absorber may be provided in the receptor, support, non-transferable intermediate layer, transferable spacer layer or adhesive layer.

The transferable spacer layer can be a composite or non-composite organic material comprising particles having a gap dimension that is less than or greater than its thickness. If the spacing dimension of the particles is less than or equal to the thickness of the deliverable spacer layer, the thickness of the transferable layer adjusts the spacing distance between the additional substrate and the receptor attached to the spacer element in forming the flat panel display device. If the spacing dimension of the particles is greater than the thickness of the deliverable spacer layer, the spacing dimension of the particles controls the spacing distance in the flat panel display.

In another embodiment, (1) providing a thermal transfer donor sheet as described above, (2) positioning the receptor in intimate contact with a transferable spacer layer of the thermal transfer donor sheet, and (3) at least Irradiating one thermal transfer donor sheet or receptor with image radiation in an imagewise pattern such that a radiation absorber of either the receptor or thermal transfer donor sheet configuration absorbs portions of the image radiation and converts the image radiation into heat; (4) transferring the transferable spacer layer in the irradiated region to the receptor, and (5) removing the thermal transfer donor sheet to form a spacer element corresponding to the irradiated region on the receptor. A process for selectively positioning spacer elements on a receptor for use is described.

In yet another embodiment, (6) attaching a spacer element to the substrate to form a cavity between the substrate and the receptor, (7) filling the cavity with liquid crystal material, and (8) the receptor around the substrate A process used to construct a liquid crystal display device further comprising the step of sealing is described.

“Intimate contact” described herein means that sufficient contact between the two surfaces can be achieved during the imaging process to provide sufficient material transfer within the thermally treated area. In other words, there is no binding in the imaged region that represents the article non-functional.

A "spacer" or "spacer element" provides a means for separating two parallel substrates (or supports) and may provide structural retention for one or both of the same parallel substrates.

"Interval dimension" refers to the distance distance between two parallel substrates provided by a spacer element. For these spacer elements based on uncomposed organic material or composition material, the composite includes particles smaller than the thickness of the transferable spacer layer, and the spacing dimension is equal to the thickness of the spacer layer. However, if the composite includes particles having a spacing dimension greater than the thickness of the transferable spacer layer, the spacing dimension is equal to the diameter or height of the particles having a direction perpendicular to the substrate. In other words, if the particle shape is spherical, the diameter of the sphere will be the measured dimension. If the shape of the particle is cylindrical (ie rod), then the cylindrical dimension is used if the circular dimension of the cylindrical particle is perpendicular to the substrate. However, if the length of the cylindrical particles is in a direction perpendicular to the substrate (ie filler between the substrates), the height of the cylinder is used as the gap dimension.

"Image radiation" refers to the energy from a radiation source that performs an imaging transfer of a large scale transfer layer from a thermal transfer donor sheet to a receptor (or substrate).

The present invention relates to a method for positioning a spacer element on a receptor (or substrate) for use in a flat panel display. The spacer element comprises a thermal transfer donor sheet comprising (a) a support, (b) an optional photothermal conversion layer, (c) an intermediate layer that is not selectively transferable, (d) a spacer layer that is transferable, and (e) an optional adhesive layer in that order. It is placed on the receptor by selective irradiation. The process comprises (i) intimate contact between the receptor described above and the thermal transfer donor sheet, and (ii) at least one thermal transfer donor with image radiation to provide sufficient heat to the irradiated area to transfer the spacer layer to the receptor. Irradiating the sheet or receptor (or part of the receptor, i.e., substrate, spacer layer, intermediate layer, photothermal conversion layer, and / or adhesive layer), and (i) transferring the transferable spacer layer in the irradiation area to the receptor. Include.

The thermal transfer donor sheet of the present invention can be provided by attaching the above-described layers (b), (c), (d) and / or (e) to the support. The support may be composed of any material known to be useful as a support for the thermal transfer donor sheet. The support may be a rigid sheet material such as glass or flexible film. The support can be flat or rough and can be transparent, opaque, translucent, sheet or non-sheet. Suitable film supports are polyester, in particular polyethylene, terephthalate (PET), polyethylene naphthalate (PEN), polysulfone, polystyrene, polycarbonate, polyimide, polyamide, and cellulose esters such as cellulose acetate and cellulose butyrate, polyvinyl Chlorides and derivatives thereof, copolymers having one or more of the above materials. Typical thicknesses of the support range from about 1 to 200 microns.

The transferable spacer layer may comprise a composite having an organic material or an organic material to which particles or fibers are bound. Suitable materials include any number of known polymers, copolymers, oligomers and / or monomers. Suitable polymeric binders include phenolic resins (ie novolak and resol resins), polyvinylacetate, polyvinylidene chloride, polyacrylates, cellulose ethers and esters, nitrocellulose, polycarbonates, polysulfones, polyesters, styrene / acrylo Nitrile polymers, polystyrene, cellulose ethers and esters, polyacetals, (methyl) acrylate polymers, polyvinylidene chloride, α-chloroacrylonitrile, maleic acid resins and copolymers, polyimides, poly (amic acid), and poly (Amide esters) and mixtures thereof, and materials such as thermosetting resins, thermosetting or thermoplastic polymers.

If the transferable spacer layer comprises a thermosetting binder, the thermosetting binder may be crosslinked after being transferred to the receptor. The binder can be crosslinked by any method suitable for a particular thermosetting binder, for example by exposing the thermosetting binder to heat and irradiating with a suitable radiation source or chemical curing agent.

Particles or fibers may be added to the transferable spacer layer to form the composite. Adding particles or fibers to the transferable spacer layer can be accomplished using any known particle or fiber having a spacing dimension that is less than or equal to the spacing required for the particular display device involved. The particles can have a spacing dimension that is less than the thickness of the transferable spacer layer or a spacing dimension that is greater than the thickness of the transferable spacer layer. The particle size is smaller and the thickness of the transferable spacer layer controls the spacing in the display device. On the other hand, if larger particles are used, the spacing dimension of the particles used in the composite controls the spacing in the display device. It is preferred that at least 5% of the particles have a larger gap dimension than the thickness of the spacer layer, with at least 10% being more preferred. Any of the above methods can be used as a means to achieve uniform separation and support of the substrate in the display. Suitable particles include organic and / or inorganic materials (solid or hollow) with appropriate shapes (ie spheres, rods, posts, triangles and trapezoids) and size distributions while maintaining the desired separation. Preferred particles include Japanese Laid-Open Patent Application Hei 7 [1995] -28068; Current LCD spacer spheres, rods, etc., made of glass or plastic, as described in US Pat. Nos. 4,874,461, 4,983,429, 5,389,288. For LCD displays, the standard deviation for particle size distribution is preferably + 20% or -20% of the mean particle spacing dimension (ie, mean diameter of cylindrical particles or mean height of cylindrical particles). More preferably, the standard deviation is + 10% or -10% of the mean, most preferably + 5% or -5%. If a fiber is used, the dimension is usually measured as the denier (or thickness) of the fiber. The length of the fiber is preferably smaller than the diameter of the transferred spacer element.

Dispersants, surfactants and other additives (ie, antioxidants, light stabilizers and coating aids) may be included to disperse the particles and / or fibers or to impart other desirable properties to the transferable spacer layer known to those skilled in the art. have.

Particles having forces in the display (eg, particles where the spacer layer includes particles having a particle spacing dimension greater than the thickness of the transferable spacer layer, and particle spacing dimensions larger than the thickness of the spacer layer the spacer layer can deliver) The compressibility of the transferable spacer layer when it does not include particles having s should be sufficient to maintain a uniform gap gap in the corresponding display.

Thermal transfer donor sheets are also useful as large-scale transfer donor sheets such as radiation (or light) absorbing materials that absorb image radiation and convert radiation energy into thermal energy to facilitate transfer of the transferable spacer layer from the donor sheet to the receptor. It may include other known components. The radiation absorber can be any material known in the art that absorbs some of the incident image radiation and converts the image radiation energy into thermal energy. Suitable radiation absorbents include organic or inorganic pigments, metals or metals which may be absorbing dyes (i.e. dyes that absorb light at ultraviolet, infrared or visible wavelengths), binders or other polymeric materials, black or non-black bodies. Membrane, or other suitable absorbent may be included.

An example of a radiation absorber known to be particularly useful is an infrared absorbing dye. Such dyes are disclosed in 1990, New York, Infrared Absorbing Materials , Plenum Press, Matsuoka, M, and 1990, Tokyo, Bunshin Publishing Co., Absorption Spectra of Dyes for Diode Lasers , Matsuoka, M, and US Patent No. 4,772,583, No. 4,833,124, 4,912,083, 4,942,141, 4,948,776, 4,948,777, 4,948,778, 4,950,639, 4,940,640, 4,952,552, 5,023,229, 5,024,990,604,5,286,340,5,269 5,401,607 and European Patents 321,923 and 568,993. In 1993, by Chem. Soc., Chem. Commun ., 452 and US Pat. No. 5,360,694 describe additional dyes. IR absorbers sold by American Cyanamid or Glendale Protective Technologies may be used under the names IR-99, IR-126 and IR-165, which are described in US Pat. No. 5,156,938. In addition to conventional dyes, US Pat. No. 5,351,617 discloses the use of IR absorbing conductive polymers as radiation absorbers.

Other examples of preferred radiation absorbers include organic and inorganic absorbers such as carbon black, metals, metal oxidants, or metal sulfides. Representative metals include not only metallic elements of groups Ib, IIb, IIIa, IVa, IVb, Va, Vb, VIa, VIb and Group V of the periodic table, but also alloys thereof or those having elements of groups Ia, IIa and IIIb. Alloys or mixtures thereof. Particularly preferred metals include Al, Bi, Sn, In, or Zn and their alloys or alloys thereof having elements of the groups Ia, IIa and IIIb in the periodic table, or composites or mixtures thereof. Suitable compounds of these metals include sulfides of metal oxides, Al, Bi, Sn, In, Zn, Ti, Cr, Mo, W, Co, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zr and Te and these Mixtures thereof.

The radiation absorber may be provided as a separate layer in the thermal transfer donor sheet, which is called a "light to heat conversion layer" (LTHC) interposed between the support and the transferable spacer layer. Typical light-to-heat conversion layers include one or more layers of organic or inorganic materials that are capable of absorbing image radiation and are preferably thermally stable. It is also desirable for the photothermal conversion layer to remain substantially complete during the imaging process. In the case where the metallic thin film is used as the photothermal conversion layer, the metal layer preferably has a thickness of 0.001 to 10 µm, more preferably 0.002 to 1.0 µm.

In addition, the light-to-heat conversion layer may be composed of light absorbing particles (ie, carbon black) dispersed in the binder. Suitable binders include thermoplastics such as thermosetting resins, thermosetting or phenolic resins (i.e., novolak and resol resins) polyvinylacetate, polyvinylidene chloride, polyacrylates, cellulose ethers and esters, nitrocellulose, polycarbonates, and mixtures thereof. Film forming polymers such as polymers are included. When this type of photothermal conversion layer is used, the dry coating thickness is preferably 0.05 to 5.0 탆, more preferably 0.1 to 2.0 탆.

If an LTHC layer is presented, an optional non-transferable intermediate layer can be inserted between the transferable spacer layer and the LTHC layer. The combination of the intermediate layers reduces the degree of contamination of the image transferred from the photothermal conversion layer, and reduces the amount of distortion in the transferred image. The intermediate layer can be an organic or inorganic material. In order to minimize the damage and contamination of the transferred spacer elements, the intermediate layer has high heat resistance, and a continuous coating that remains intact and contacts the LTHC layer during the imaging process is preferred. Suitable organic materials include both (crosslinked) thermosetting resins and thermoplastic materials. The intermediate layer can be transmissive or reflective at the image radiation wavelength output.

Suitable thermosetting resins useful for the interlayer include both thermally crosslinked and radiation crosslinked materials such as crosslinked poly (methyl) acrylates, polyesters, epoxies and polyurethanes. To facilitate the application, the thermosetting resin material is generally coated on the photothermal conversion layer as a thermoplastic precursor and then crosslinked to form the desired crosslinking intermediate layer. Suitable thermoplastic materials include polysulfones, polyesters and polyimides. The thermoplastic interlayer can be applied to the photothermal conversion layer using conventional coating techniques (ie, solvent coating, spray coating or extraction coating). The optimum thickness of the intermediate layer is determined by the minimum thickness in the transfer of the photothermal conversion layer, and the distortion of the transferred spacer layer is usually removed between 0.05 and 10 mu m.

Inorganic materials suitable for use as interlayer materials include metals, metal oxidants, metal sulfides and inorganic carbon coatings, which have high permeability at the wavelength of image radiation and employ conventional techniques (ie vacuum sputtering, vacuum evaporation or plasma jet). Can be applied to the photothermal conversion layer. The optimum thickness is determined by the minimum thickness at the time of transfer of the photothermal conversion layer, and the distortion of the transferred layer is usually removed between 0.01 and 10 mu m.

The thermal transfer donor sheet may comprise an optional adhesive layer coated on the surface of the transferable spacer layer. The adhesive layer improves transfer to the transferable spacer layer to the receptor by thermally activated adhesive. Adhesive topcoats are preferably colorless, but in some applications translucent or opaque adhesives may be used to increase the contrast of the display or to provide a particular effect. It is preferable that an adhesive layer is not adhesive at room temperature. The adhesive layer may also include a light absorbing material to aid in the transfer efficiency of the image. Preferred adhesives include thermoplastic materials having a melting temperature between approximately 30 ° C and 110 ° C. Suitable thermoplastic adhesives include materials such as polyamides, polyacrylates, polyesters, polyurethanes, polyolefins, polystyrenes, polyvinyl resins, copolymers, and combinations thereof. The adhesive may also include a thermal or photochemical crosslinker to provide thermal stability and solvent durability for the transferred image. Crosslinkers include monomers, oligomers, and polymers that can be thermally or photochemically crosslinked by external initiator systems or internal self-initiating groups. Thermal crosslinkers include materials that can crosslink when thermal energy is applied.

The radiation absorber also binds to an individual topcoat (i.e., a black matrix on the receptor, an adhesive topcoat attached to the receptor's surface) to bind to the receptor or to aid in the transfer of the spacer layer to the receptor. Can be. If the radiation absorber is provided to the receptor or to a portion of the thermal transfer donor sheet transferred to the receptor during the imaging process, the radiation absorber preferably does not interfere with the performance characteristics (ie, desirable optical properties) of the imaged receptor.

The receptor may be any flat panel display element that benefits from the application of the spacer. The spacer is precisely placed in the desired position to avoid optical interference in the display window of the display device. The receptor may be optionally coated with an adhesive topcoat to facilitate transferring the transferable spacer layer to the receptor. The receptor can also have a black matrix attached to its surface to enhance visual contrast. The black matrix can be formed by attaching an inorganic (ie, metal and / or metal oxidant, metal sulfide) or organic material (ie, a dye of an organic binder) or a combination thereof (ie, carbon black dispersed in a binder). Black matrices typically have a thickness between 0.005 and 5 microns. Typically the receptor has a thickness between 1 and 2000 microns.

In the practice of the present invention, the thermal imaging device is positioned in accordance with the application of image radiation (or light), and the LTHC layer is irradiated to form a spacer element on the receptor by absorbing the image radiation and converting it into heat in the irradiated area. It is possible to improve the transfer of the transferable spacer layer in the region.

Formation of the spacer may be effected by proper modulation of the image radiation source or exposure through the mask. The spacer can be precisely placed in the desired position to avoid optical interference in the display window of the display device. Various light radiation sources in the present invention include flash lamps, high power gas lasers, infrared, visible and infrared lasers. In analog systems, a mask is used to selectively filter the irradiation to an imaged pattern corresponding to the desired spacer position. Flash lamps with sufficient energy output to transfer spacer layers can be used in analog systems. In digitally processed systems, lasers or laser diodes are used to imageically transfer a spacer layer onto a substrate at a desired spacer location. Preferred lasers for use in the present invention include high power (> 100 mW) single mode laser diodes, fiber coupled laser diodes and diode pumped solid state lasers (ie, Nd: YAG and Nd: YLF), Preferred lasers are diode pumped solid state lasers. In both analog and digitally processed systems, the spacers can be accurately positioned in the desired position to avoid optical interference in the display window of the display device. Since the spacers are selectively transferred from the thermal transfer element to the substrate, no liquid processing step is required to develop the image. Direct imaging processes do not require additional equipment, additional steps to develop the image, and attachment of consumable developer.

During laser exposure, it is desirable to minimize the formation of interference patterns by multiple reflections from the imaged material. This can be accomplished by various methods. The most common method is to effectively roughen the surface of the thermally imageable device according to the incident image radiation dose as disclosed in US Pat. No. 5,089,372. Another method is to use an anti-reflection coating on the second surface on which the incident light impinges. The use of antireflective coatings is known in the art and may be configured with a quarter wavelength thickness of a coating such as magnesium fluoride, as disclosed in US Pat. No. 5,171,650. Because of cost and manufacturing limitations, surface roughness methods are preferred in many applications.

A representative application of the process for using the thermal transfer donor sheets described herein to selectively place spacers on a substrate is in the manufacture of liquid crystal display devices. A twisted nematic display device is an example of a typical liquid crystal display, which includes a cell or envelope formed by mating and arranging a pair of transparent planar substrates spaced apart from each other using spacer elements. . The outer circumference of the substrate is bonded and sealed by an adhesive sealant commonly used by shield printing techniques to provide a sealed cell. Shallow spaces or cavities between spacer elements on the substrate are filled with liquid crystal material just prior to final sealing. The conductive transparent electrode is aligned to the inner surface of the substrate in a segmented or X-Y matrix design to form a plurality of image elements. Alignment coating is applied to the inner surface portion of the liquid crystal display cell to have the desired orientation of the liquid crystal material at the point bordering the surface of the display. This causes the liquid crystal to rotate the light at an angle that is complementary to the alignment of the polarizers associated with the cell. The polarizing elements are optional depending on the type of display and may be associated with one or more surfaces of the display when in use. The reflector element can be associated with the bottom substrate when the transmissive display is desired to be reflective. In this case, the bottom substrate may not be transparent. The receptor may optionally include an alignment layer coated on the surface, in which case a spacer is used for the alignment layer. The spacer is placed on the receptor (or alignment layer) using the previously described process by selectively irradiating the thermal transfer donor element in intimate contact with the receptor.

The components and assembly techniques of the liquid crystal displays described above are known. For example, a general detailed description of an assembly can be found in World Scientific Publishing Co. Pte. Ltd., Volume 1, Chapter 7 (1990), in Bitendra Bahadur, Ed., "Materials and Assembling Process of LCDs," Liquid Crystals-Applications and Uses.

The examples for illustrating the invention described below do not limit the invention.

Example

The materials adopted below are from Aldrich Chemical Co. (Milwaukee, WI) unless otherwise specified.

The following examples illustrate forming a spacer on a glass substrate using the following process. Spacers were formed on the glass substrate by placing the coated side of the thermal transfer donor element in intimate contact with the organic substrate in the recessed vacuum frame and imaged using a single mode Nd: YAG laser in a flat field scanning configuration. The laser was incident on the substrate surface of the thermal transfer element and was normal to the transfer element / glass receptor surface. Scanning was performed by a linear galvanometer focused on the image plane using an f-theta scan lens. The power on the image plane was 8 watts and the laser spot size (measured in 1 / e ² intensity) was 140 × 150. The linear laser spot velocity was 4.6 meters per second as measured in the image plane.

Example 1

The carbon black photothermal conversion layer was provided by coating LTHC Coating Solution 1 with a # 9 coating rod on a 0.1 mm (3.88 mil) PET substrate.

LTHC Coating Solution 1:

The coating was dried at 80 ° C. for 3 minutes, UV cured on a Fusion UV cured model MC-6RQN equipped with 300 w / inch H-bulb and a web transport of 22.9 m / min (75 ft./min) web transport speed was used. The cured coating had a thickness of 3 microns and the light thickness was 1.2 at 1064 nm.

Protective Interlayer Solution 1 was coated onto the carbon black coating of the photothermal conversion layer using a # 4 coating rod.

Protective Interlayer Solution 1:

The coating was dried at 80 ° C. for 3 minutes, UV cured on a Fusion UV Curing Model MC-6RQN equipped with 300 w / inch H-bulbs and a web transport of 22.9 m / min (75 ft./min). web transport speed was used. The cured coating had a thickness of 1 micron.

The intermediate layer was coated with Transferable Spacer Layer Coating Solution 1 provided below.

Transferable Spacer Layer Coating Solution 1

Four separate coatings were made using # 4, # 6, # 8 and # 10 wire wound bars and all coatings were dried at 60 ° C. for 3 minutes. As a result, the thickness of the dried coating on the four samples ranged from 1 to 2 microns.

The thermal transfer device was imaged on a 75 mm x 50 mm x 1 mm glass slide using the laser imaging system described above. The spacer layer was successfully transferred to the glass to provide parallel lines approximately 95 microns wide. It has also been demonstrated that the thickness of the transferred spacers can be increased by transferring additional spacer layers on previously transferred spacers to form spacer lines that are several times higher than the original transferred spacer lines. This was accomplished by replacing the imaging step with an additional thermal transfer element having the position of the transfer line registered at the position of the previously transferred spacer.

Example 2

This embodiment shows a thermal transfer device having a composite transferable spacer layer comprising silica particles having a particle spacing dimension smaller than the thickness of the spacer transfer layer.

The carbon black photothermal conversion layer is 0.1 mm (3.88 mil) on a Yasui Seiki Lab Coater, model CAG-150, using a microgravure roll of 228.6 helical cells per line cm (90 helical cells per line inch). ) Was provided by coating the following LTHC Coating Solution 2 on PET.

LTHC Coating Solution 2

The coating was dried in-line at 40 ° C. and 6.1 m / min using a Fusion Systems Model I600 (400 Watts / inch) UV curing system installed in H-bulb. UV cured at (20 ft./min.). The dried coating had a thickness of approximately 3.5 microns and an optical density of 1.2 at 1064 nm.

Carbon black coating of the light-heat conversion layer was a Yasui Seiki Lab Coater, Model CAG- 150 using a wheeling [Roto] gravure (rotogravure) protected intermediate layer coating fluid 2 coated with (Protective Interlayer Coating Solution 2). The coating was dried in-line at 40 ° C. and 6.1 m / min using a Fusion Systems Model I600 (400 Watts / inch) UV curing system installed in H-bulb. UV cured at (20 ft./min.). As a result, the thickness of the interlayer coating was about 1 μm. This LITI donor element was designated as "LITI Donor Element I".

Protective Interlayer Coating Solution 2

The protective interlayer of LITI Donor Element I was coated with the following Transferable Spacer Layer Coating Solution 2 using a # 10 wire wound bar and rolled at 60 ° C. for 2 minutes. The thickness of the rolled coating was determined to be approximately 2.7 microns by profilometry.

Transferable Spacer Layer Coating Solution 2

The spacer layer of the thermal transfer element (organic binder / SiO ₂ coating) is placed in intimate contact with a 75 mm x 50 mm x 1 mm glass slide receptor, approximately 60 microns wide and 2.7 microns thick with a center-to-center spacing of 400 microns. It was imaged in the form of an image using the procedure described above to transfer the spacer lines with. After imaging, the imaged glass receptors were heated to 250 ° C. in a nitrogen atmosphere for 1 hour to cross the spacer lines.

Example 3

This embodiment shows a thermal transfer device having a composite transferable spacer layer comprising particles having a gap dimension greater than the thickness of the transferable spacer layer.

The protective interlayer of LITI Donor Element I in Example 2 was transferred to the Transferable Spacer Layer Coating Solution 3 using the same process as described in Example 2 to coat the transferable spacer layer coating solution 2 . Overcoated.

Transferable Spacer Layer Coating Solution 3

The spacer layer of the thermal transfer element (organic binder / ZrO ₂ coating) is placed in intimate contact with a 75 mm × 50 mm × 1 mm glass slide receptor and is approximately 105 microns wide and 3.0 microns thick with a center-to-center spacing of 300 microns. It was imaged in the form of an image using the procedure described above to transfer the spacer lines with. After imaging, the imaged glass receptors were heated to 250 ° C. in a nitrogen atmosphere for 1 hour to cross the spacer lines.

Claims (10)

A method for selectively placing a spacer in a receptor for a flat panel display, the method comprising: (Iii) providing a thermal transfer donor sheet having (a) a support, (b) a transferable spacer layer, and (c) an optical adhesive layer in that order, and a receptor, wherein the receptor, support, transferable spacer At least one of the layer and the optical adhesive layer comprises a radiation absorber, (Ii) placing the receptor in intimate contact with the transferable spacer layer of the thermal transfer donor sheet; (Iii) at least one of the thermal transfer donor sheet and the receptor is image radiation that is absorbed by the radiation absorber and converted to sufficient heat to transfer the irradiated region of the transferable spacer layer of the thermal transfer donor sheet to the receptor. Irradiating with an image-like pattern, (Iii) transferring the transferable spacer layer in the irradiated region to the receptor, (Iii) removing the thermal transfer donor sheet to form a spacer element corresponding to the irradiated area on the receptor. In the method for selectively placing a spacer in the receptor for a flat panel display, (Iii) a thermal transfer donor sheet comprising (a) a supporting portion, (b) a photothermal conversion layer having a first radiation absorbing agent, (c) a transferable spacer layer, and (d) an optical adhesive layer in that order, the first and the first Providing a receptor having two surfaces, (Ii) disposing the first surface of the receptor in intimate contact with the transferable spacer layer of the thermal transfer donor sheet; (Iii) at least one of the thermal transfer donor sheet and the receptor is absorbed by the first radiation absorber and sufficient to transfer the irradiated region of the transferable spacer layer of the thermal transfer donor sheet to the first surface of the receptor. Irradiating with an image-type pattern with image radiation converted into heat; (Iii) transferring the transferable spacer layer in the irradiated area to the first surface of the receptor, (Iii) removing the thermal transfer donor sheet to form a spacer element corresponding to the irradiated area on the first surface of the receptor. The method of claim 2, At least one of the receptor, support, transferable spacer layer and optical adhesive layer comprises a second radiation absorber that absorbs the image radiation. The method of claim 2, And a non-transferable intermediate layer interposed between the photothermal conversion layer and the transferable spacer layer of the thermal transfer donor sheet. The method of claim 4, wherein At least one of said receptor, support, non-transferable interlayer and transferable spacer layer comprises a second radiation absorber which absorbs said image radiation and converts said radiation into heat. The method of claim 2, And the receptor further comprises an adhesive topcoat layered on the first surface. The method of claim 2, And the transferable spacer layer is a composite consisting of particles having a spacing dimension smaller than the thickness of the spacer layer. The method of claim 2, And said transferable spacer layer is a composite consisting of particles having an average spacing dimension greater than the thickness of said spacer layer. The method of claim 2, (Iii) attaching the spacer element to the substrate to form a cavity between the receptor and the substrate; (Iii) filling the cavity with liquid crystal material; (Iii) sealing the periphery of the substrate to the receptor. A thermal transfer donor sheet suitable for use in selectively placing spacers in a receptor in a flat panel display, comprising: (Iii) the support, (Ii) a photothermal conversion layer having a first radiation absorber that absorbs a first portion of the image radiation and converts the first portion of the image radiation into heat; (Iii) a transferable spacer layer composed of a composite of particles dispersed in a binder and having a mean spacing dimension greater than the thickness of the transferable spacer layer; (Iii) A thermal transfer donor sheet comprising an optical adhesive layer.